Apple Inc.

Sun Microsystems, Inc.

P.a. Semi, Inc.

Shyam Sundar

Gerard Richard Williams

Ronald P Hall

Ramesh B Gunna

Ian D Kountanis

Wei-Han Lien

Conrado Blasco

Peter F Lai

Conrado Blasco-Allue

Rambabu Pyapali

Aveek Sarkar

André Seznec

James B Keller

Sandeep Kumar Gupta

John H Mylius

Richard F Russo

Rajat Goel

Yu-Yen Mo

Fang Liu

Kong-Fai Woo

Venkat R Podduturi

Sachin Chopra

John K Yong

Teong Ming Cheah

Vishal Chopra

A system and method for reducing the latency of data move operations. A register rename unit within a processor determines whether a decoded move instruction qualifies for a zero cycle move operation. If so, control logic assigns a physical register identifier associated with a source operand of the move instruction to the destination operand of the move instruction. Additionally, the register rename unit marks the given move instruction to prevent it from proceeding in the processor pipeline. Further maintenance of the particular physical register identifier may be done by the register rename unit during commit of the given move instruction.

Zero cycle move using free list counts

A processor includes a mechanism for disabling a memory array of a branch prediction unit. The processor may include a next fetch prediction unit that may include a number of entries. Each entry may correspond to a next instruction fetch group and may store an indication of whether or not the corresponding the next fetch group includes a conditional branch instruction. In response to an indication that the next fetch group does not include a conditional branch instruction, the fetch prediction unit may be configured to disable, in a next instruction execution cycle, the memory array of the branch prediction unit.

Fetch predition circuit for reducing power consumption in a processor

Reducing power consumption in a processor

A system and method for efficiently indicating branch target addresses. A semiconductor chip predecodes instructions of a computer program prior to installing the instructions in an instruction cache. In response to determining a particular instruction is a control flow instruction with a displacement relative to a program counter address (PC), the chip replaces a portion of the PC relative displacement in the particular instruction with a subset of a target address. The subset of the target address is an untranslated physical subset of the full target address. When the recoded particular instruction is fetched and decoded, the remaining portion of the PC relative displacement is added to a virtual portion of the PC used to fetch the particular instruction. The result is concatenated with the portion of the target address embedded in the fetched particular instruction to form a full target address.

Immediate branch recode that handles aliasing

Various techniques for processing and pre-decoding branches within an IT instruction block. Instructions are fetched and cached in an instruction cache, and pre-decode bits are generated to indicate the presence of an IT instruction and the likely boundaries of the IT instruction block. If an unconditional branch is detected within the likely boundaries of an IT instruction block, the unconditional branch is treated as if it were a conditional branch. The unconditional branch is sent to the branch direction predictor and the predictor generates a branch direction prediction for the unconditional branch.

IT instruction pre-decode

A system and method for efficiently performing microarchitectural checkpointing. A register rename unit within a processor determines whether a physical register number qualifies to have duplicate mappings. Information for maintenance of the duplicate mappings is stored in a register duplicate array (RDA). To reduce the penalty for misspeculation or exception recovery, control logic in the processor supports multiple checkpoints. The RDA is one of multiple data structures to have checkpoint copies of state. The RDA utilizes a content addressable memory (CAM) to store physical register numbers. The duplicate counts for both the current state and the checkpoint copies for a given physical register number are updated when instructions utilizing the given physical register number are retired. To reduce on-die real estate and power consumption, a single CAM entry is stores the physical register number and the other fields are stored in separate storage elements.

RDA checkpoint optimization

A circuit for implementing a branch target buffer. The branch target buffer may include a memory that stores a plurality of entries. Each entry may include a tag value, a target value, and a prediction accuracy value. A received index value corresponding to an indirect branch instruction may be used to select one of entries of the plurality of entries, and a received tag value may then be compared to the tag value of the selected entries in the memory. An entry in the memory may be selected in response to a determination that the received tag does not match the tag value of compared entries. The selected entry may be allocated to the indirect instruction branch dependent upon the prediction accuracy values of the plurality of entries.

Usefulness indication for indirect branch prediction training

Various techniques for processing instructions that specify multiple destinations. A first portion of a processor pipeline is configured to split a multi-destination instruction into a plurality of single-destination operations. A second portion of the pipeline is configured to process the plurality of single-destination operations. A third portion of the pipeline is configured to merge the plurality of single-destination operations into one or more multi-destination operations. The one or more multi-destination operations may be performed. The first portion of the pipeline may include a decode unit. The second portion of the pipeline may include a map unit, which may in turn include circuitry configured to maintain a list of free architectural registers and a mapping table that maps physical registers to architectural registers. The third portion of the pipeline may comprise a dispatch unit. In some embodiments, this may provide certain advantages such as reduced area and/or power consumption.

Processing multi-destination instruction in pipeline by splitting for single destination operations stage and merging for opcode execution operations stage

In one embodiment, a renamer comprises a plurality of storage locations and compare circuitry. Each storage location is assigned to a respective renameable resource and is configured to store an identifier corresponding to a youngest instruction operation that writes the respective renameable resource. Coupled to receive an input representing one or more retiring instruction identifiers corresponding to instruction operations that are being retired, the compare circuitry is configured to detect a match between at least a first identifier in a first storage location and one of the retiring identifiers. An encoded form of the identifiers is logically divided into a plurality of fields, and the input comprises a first plurality of bit vectors. Each of the first plurality of bit vectors corresponds to a respective field and includes a bit position for each possible value of the respective field.

Partially decoded register renamer

The present invention describes a method and an apparatus for determining switching power consumption of global devices (e.g., repeaters, flops or the like) in an integrated circuit design during high-level design phase after the global routing for the integrated circuit is available. The clock cycle is divided into various timing intervals and the timing reports are generated for each cycle to determine a time-domain staggered distribution of each device's switching activity within a given timing interval. Each device's switching activity is analyzed within the given timing interval (or segment thereof). The power consumption is determined for each device that switches in the given timing interval.

Method and apparatus for power consumption analysis in global nets

The present application describes various embodiments of a method and an apparatus for determining electromigration risks for signal nets in integrated circuits. A model for each one of the global nets connecting various circuit blocks in an integrated circuit is created using circuit blocks' timing model and detailed standard parasitic format representation (DSPF) of each global net. The final layout of the integrated circuit is not necessary to determine the electromigration risks. The models can be generated during the early stages of the design cycle once the DSPF of the global nets is available.

Method and apparatus for signal electromigration analysis

The present invention describes a method and apparatus for placing flops in a complex circuit design. Initially, the method calculates a physical range for every net that requires a flop, within which the flop can be placed satisfying the timing requirement. After the physical range is defined, the method groups these flops and determines a block where these grouped flops can be placed. Grouping these flops into one block (flop station) can preserve a compact layout for the design. The flops are then connected to appropriate nets.

Growing community of inventors

Sunnyvale, CA, United States of America

Shyam Sundar